As a control device for a vehicle including an internal combustion engine as a power source, there is known a vehicle integrated control device that performs control of the internal combustion engine by integrating the control of the internal combustion engine with control of an automatic transmission and a braking device. The vehicle integrated control device is configured by a drive system manager that manages an operation of an entire drive system, an engine control unit that controls the internal combustion engine, a transmission control unit that controls the automatic transmission, a brake control unit that controls the braking device and the like.
In the conventional vehicle integrated control device, torque demand control has been adopted as the method for controlling an internal combustion engine. According to the torque demand control, a request torque is given to the engine control unit from the drive system manager. The request torque includes a driver request torque that is requested by the driver. Furthermore, the request torque includes system request torques that are requested by on-board systems such as a sprung vibration damping control system, a transmission control unit, and a vehicle attitude stability control system. The engine control unit determines an operation amount of the actuator of the internal combustion engine, for example, a throttle, based on the given request torque.
The drive system manager determines a request torque that should be given to the engine control unit by mediating between the request for the torque from the driver and the requests for the torques from the on-board systems. Subsequently, the engine control unit operates the actuators such as the throttle in order to realize the request torque given by the drive system manager. However, depending on the magnitude of the request torque, the request torque cannot be always realized by the internal combustion engine. This is because there is an upper limit to the torque which can be realized by the internal combustion engine. More specifically, in the case of a naturally aspirated internal combustion engine, the torque outputted by the internal combustion engine becomes maximum by fully opening the throttle. The maximum torque does not have a fixed value, but has a variable value that varies in accordance with the engine speed. Furthermore, in the case of an internal combustion engine equipped with a supercharger, the maximum torque capable of being outputted by the internal combustion engine varies in accordance with the supercharging state. Namely, a difference occurs to the torque at the time of the throttle being fully opened depending on whether the supercharging pressure is high or low. The supercharging pressure can be actively controlled by an actuator, for example, a wastegate valve. Accordingly, in the case of the internal combustion engine equipped with a supercharger, which includes a wastegate valve, the torque which is obtained when the throttle is fully opened, and the wastegate valve is completely closed is the maximum torque of the internal combustion engine.
Even if the request torque which exceeds the maximum torque is given to the engine control unit, the internal combustion engine cannot output a torque that exceeds the maximum torque. Further, even if the actuator is operated based on the request torque which cannot be realized by any possibility, drivability would be only degraded. In order to extract the operation performance of the internal combustion engine sufficiently, it is important to give an appropriate request torque to the engine control unit, and in order to do so, the maximum torque capable of being outputted by the internal combustion engine needs to be grasped at the side of the drive system manager.
However, when the control target is an internal combustion engine equipped with a supercharger, an appropriate request torque cannot be determined by only grasping the maximum torque. The request torque which is given to the engine control unit includes a request regarding the magnitude of a torque and a request regarding a change speed of the torque, as information. The maximum torque of the internal combustion engine equipped with a supercharger is the torque which is obtained when the throttle is fully opened, and the wastegate valve is completely closed, and in the entire region of the torque range which does not exceed the maximum torque, the torque change speed which is requested cannot be always realized. This is because while the response speed of the torque to the operation of the throttle is high, the response speed of the torque to the operation of the wastegate valve is low. When the magnitude of the request torque is in the torque range in which an operation of the wastegate valve is required, and the request torque includes a torque component with a high change speed, the torque component with the change speed is unlikely to be realized. In order to prevent control of the internal combustion engine based on a request torque which is unrealizable, it is demanded to give an appropriate request torque including not only a magnitude but also a change speed to the engine control unit.
Note that an internal combustion engine equipped with a supercharger is described as an example here, but the above described problem is a problem that is also applicable to a certain kind of naturally aspirated internal combustion engine. In the internal combustion engine which controls the intake air amount by two kinds of actuators that are provided upstream and downstream of the intake passage, such as an internal combustion engine including a throttle and an intake valve equipped with a variable lift mechanism, there is a difference between the control range of the torque by only the downstream side actuator, and the control range of the torque by an operation of both the actuators. Furthermore, there is also a difference between the response speed of the torque to an operation of the downstream side actuator, and the response speed of the torque to an operation of the upstream side actuator. Accordingly, it is also demanded to give an appropriate request torque including not only a magnitude but also a change speed to the engine control unit which controls the internal combustion engine like this.
The literatures listed as follows are prior art literatures showing the technological level of the technical field relating to the present application.